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Explainer: Modern slavery clauses in Illegal Migration Bill

Explainer of the modern slavery clauses in the Illegal Migration Act and legal analysis of its compatibility with international legislation.

Published: 12th July 2023

Receiving Royal Assent on 20 July 2023, the Illegal Migration Act’s provisions amend immigration, asylum, and modern slavery legislation. The purpose of the Act is to “prevent and deter unlawful migration, and in particular migration by unsafe and illegal routes”.

This Explainer aims to answer common questions about the modern slavery provisions in the Act.* It is based on a rapid assessment of what is known from research, evidence and data about the rationale for the modern slavery provisions and their potential implications and a legal analysis of the human rights compatibility of the Act’s modern slavery provisions, undertaken by Dr Marija Jovanovic and available below. This Explainer was produced by the Modern Slavery PEC’s policy impact team, alongside the PEC’s lived experience engagement team.

The authors are grateful to Dr Patrick Burland, Senior Project Officer, International Organization for Migration, and Dr Marija Jovanovic for detailed comments on a draft of this Explainer.

The first version of this Explainer was published on 28 March 2023, after the Illegal Migration Bill was introduced to Parliament on 7 March 2023. The Explainer was continuously updated as the Bill progressed through Parliament. This version analyses the final Illegal Migration Act that received Royal Assent on 20 July 2023.


  • The Illegal Migration Act presents serious implications for large numbers of people who are victims of modern slavery. It provides for the denial of support, and for the detention and deportation or removal of people who are recognised to be potential victims of modern slavery.
  • Thousands of potential victims of modern slavery will be denied protections by the modern slavery provisions in the Act, when commenced. This includes people for whom their entry to the UK is an integral element of the criminal offence of trafficking committed against them (see paragraphs 7-8).
  • The need for these provisions is predicated on the UK Government’s assumption that people are ‘abusing’ the modern slavery system, and that the system is an incentive for illegal migration to the UK. The available evidence questions both of these assumptions (see paragraphs 5-6; 9-17).
  • The modern slavery measures in the Act are incompatible with the UK’s obligations under Article 4 of the European Convention on Human Rights (ECHR), which are part of UK law under the Human Rights Act 1998 (HRA), and its obligations in international law under the European Convention Against Trafficking (ECAT) (see paragraphs 18-25).
  • The modern slavery provisions provide for the denial of protection and support for potential victims, and for their removal from the UK before the victim identification process has been completed, impacting on their safety from traffickers and their recovery from exploitation. The Act itself provides some exceptions for those supporting investigations and prosecutions, and Section 22(5) creates a presumption that survivors’ presence in the UK is not required to provide this support, unless the Home Secretary determines there are compelling circumstances. This is very likely to reduce survivors’ willingness and ability to cooperate with authorities in criminal proceedings, which often plays a central role in successful prosecutions (see paragraph 27). The Government has committed to set out in Statutory Guidance further exceptions for people exploited in the UK, but more detail is needed on how this will operate and interact with Section 22(5) of the Act (see paragraph 31).
  • The measures that are not specific to modern slavery may directly harm people affected by modern slavery who seek asylum or humanitarian protection by increasing their susceptibility to exploitation and trafficking, and by exposing them to long-term psychological harm through, for example, detention (see paragraph 29).
*The information contained in this document is not intended to be used for legal or casework purposes. Legal advice should be sought to definitively clarify individuals’ legal rights and entitlements.

The earlier versions of the Explainer: